(1) Field of the Invention
The present invention relates to a plastic container having a frosted appearance and in particular to a plastic container having a frosted and high grade appearance which is similar to that of a ground glass container.
(2) Description of the Prior Art
Since the plastic containers are light weight and excellent in shock resistance and the other mechanical properties, they have been widely used as packaging containers for various contents in lieu of glass containers. Particularly, blown containers made of an olefin resin such as polyethylene and polypropylene are much demanded since they are relatively economical and easy to mold.
The plastic containers having a frosted or matted appearance has been strongly demanded as ground glass containers having been widely used. Such containers having a frosted or matted appearance gives an impression of shade off, depth and high grade and has been demanded particularly in the field of packaging containers for cosmetic products, toiletry goods and other home use goods.
A technique which has heretofore been adopted to provide a plastic having a frosted or matted appearance comprises sand blasting the cavity surface of a mold for blow molding and transferring an embossed pattern formed on the cavity surface to the outer surface of a plastic container which is being formed. However, this technique has drawbacks that special means to perform a sand blasting on the cavity surface of the mold is necessary and that the molded containers usually do not have a satisfactory frosted or matted appearance.
It seems that these drawbacks are related with a problem that the embossed pattern of the mold surface is not reproduced on the surface of the container when the molten plastic is brought into contact with the surface of the mold and is cooled and a problem that a satisfactory frosted or matted appearance is not obtained even if the embossed pattern on the mold surface is reproduced on the surface of the container at a high fidelity.
It is considered that this is due to a fact that the glass is completely amorphous while the plastic is more or less crystalline and a fact that the glass is completely transparent while the plastic has an inner haze.